October 2. (Wednesday) 15:00, Ortvay auditory (0.81)

Dr. André K. Eckhardt

Lehrstuhl für Organische Chemie II, Ruhr-University Bochum, Germany

Preparation and Spectroscopic Characterization of Interstellar Relevant Imine Species

Simple imines are frequently used as building blocks in the synthesis of more complex molecules. In solution imines are typically prepared from carbonyl compounds and ammonia or primary amines, respectively. The simplest aldimine, formaldimine (H₂CNH), has been discovered in space but cannot be isolated on Earth due to polymerization or oligomerization when concentrated. Aldimine building blocks play a key role in the formation of biorelevant molecules like amino acids or nucleobases in prebiotic chemistry. However, spectroscopic data of the compound class are rare or missing at all due to their high reactivity and the absence of molecular precursors for an on-demand mild generation. The overall goal of this project is to learn more about interstellar and prebiotic imine chemistry and characterize often proposed but yet elusive imine species.

1,2-Diiminoethane was photochemically prepared from explosive 1,2-diazidoethane in solid argon at 3 K and characterized by infrared and UV/Vis spectroscopy. In aqueous solution the simplest diimine serves as a fundamental building block for imidazole heterocycles.

The simplest α-imino acid, namely glycine imine, was prepared by UV irradiation of azidoacetic acid in solid argon at 3 K and characterized by IR and UV/Vis spectroscopy. In aqueous solution at higher concentrations glycine imine undergoes self-reduction to glycine by oxidative decarboxylation chemistry. The imine serves a critical intermediate in prebiotic amino acid synthesis.

2-Iminoacetaldehyde was proposed as an interstellar molecule and prepared by photolysis of 2-azidoacetaldehyde in solid argon at 3 K and low density amorphous water ice. The imine was characterized by characterized by infrared and UV/Vis spectroscopy.

References

[1] A. K. Eckhardt Chem. Commun. 58, 8484–8487 (2022).

[2] V. Paczelt, R. C. Wende, P. R. Schreiner and A. K. Eckhardt Angew. Chem Int. Ed. 62, e202218548 (2023).

[3] V. D. Drabkin, V. Paczelt and A. K. Eckhardt Chem. Commun. 59, 12715–12718 (2023).

October 16. (Wednesday) 15:00, Ortvay auditory (0.81)

Univ. Prof. Dr. Hinrich Grothe

TU Wien, Institute of Materials Chemistry, Getreidemarkt 9/BC, 1060 Vienna, Austria

The efficiency of ice-nucleating macromolecules from Betula pendula pollen

Various aerosols, including mineral dust, soot, and biological particles, can act as ice nuclei, initiating the freezing of supercooled cloud droplets. Cloud droplet freezing significantly impacts cloud properties and, consequently, weather and climate. Some biological ice nuclei exhibit exceptionally high nucleation temperatures close to 0 °C. Ice Nucleating Macromolecules (INMs) found on pollen are typically not considered among the most active ice nuclei. Still, they can be highly abundant, especially for species such as Betula pendula, a widespread birch tree species in the boreal forest. Recent studies have shown that certain tree-derived INMs exhibit ice nucleation activity above ‒10 °C, suggesting they could play a more significant role in atmospheric processes than previously understood. Our study reveals three distinct INM classes active at ‒8.7 °C, ‒15.7 °C, and ‒17.4 °C are present in Betula pendula. Freeze-drying and freeze-thaw cycles noticeably alter their ice nucleation capability, and the results of heat treatment, size, and chemical analysis indicate that INM classes correspond to size-varying aggregates, with larger aggregates nucleating ice at higher temperatures in agreement with previous studies on fungal and bacterial ice nucleators. Our findings suggest that Betula pendula INMs are potentially important for atmospheric ice nucleation because of their high prevalence and nucleation temperatures.

November 14. (Thursday) 15:00, Bruckner auditory (063)

KAPUY LECTURE

Prof. Peter Knowles

Cardiff University, UK

How far can we go with single-configuration quantum chemistry?

Traditional quantum chemistry begins with the mean field model, where the orbital approximation leads to a single Slater determinant. Electron correlation effects are then introduced perturbationally, or through coupled-cluster theory, or modelled with a density functional. When correlation is strong, multiconfigurational reference methods offer a general flexible approach that avoids the qualitative failure of the Hartree-Fock reference, but they have the disadvantages of strong cost scaling with system size, and, in most cases, a lack of size extensivity. In this lecture I will explore the extent to which the useful domain of single-reference methods can be extended. The consideration will include alternative coupled-cluster formulations, new forms of perturbation theory, and extension to the correlation of electrons with vibrations (beyond Born-Oppenheimer) and photons (molecules in an optical cavity).

November 20. (Wednesday) 15:00, Ortvay auditory (0.81)

Prof. Edina Rosta

Department of Physics and Astronomy, University College London, London, UK

Enhanced Sampling Simulations of Biomolecular Systems

Phosphate catalytic enzymes are essential and ubiquitous to all forms of life. While structures of these proteins are typically readily available, prediction and design of their function and activity is a key current challenge. Here we present computing intensive free energy calculation data and machine learning applications to predict catalytic activity for prototype examples including Ras [1]. Our work highlights the important role of coupled proton transfer steps in the catalytic mechanism using the finite-temperature string method. This allows us to use multiple collective variables that govern the reaction path. Identification of these collective variables in complex processes presents a major problem. We offer promising AI-driven algorithms to help identify essential reaction coordinates in biomolecular processes [2,3].

References

[1] Berta, D.; Gehrke, S.; Nyíri, K.; Vértessy, B. G.; Rosta, E. Mechanism-Based Redesign of GAP to Activate Oncogenic Ras. JACS, 2023, 10.1021/jacs.3c04330.

[2] Badaoui, M.; Buigues, P. J.; Berta, D.; Mandana, G. M.; Gu, H.; Földes, T.; Dickson, C. J.; Hornak, V.; Kato, M.; Molteni, C.; Parsons, S.; Rosta, E. Combined Free-Energy Calculation and Machine Learning Methods for Understanding Ligand Unbinding Kinetics. J. Chem. Theory Comput. 2022, 10.1021/acs.jctc.1c00924.

[3] Buigues, PJ; Gehrke, S; Badaoui, M; Mandana, G. M.; Qi, T; Bottegoni, G; Rosta, E. Investigating the Unbinding of Muscarinic Antagonists from the Muscarinic 3 Receptor. bioRxiv; 2023, 10.1101/2023.01.03.522558.

December 4. (Szerda) 15:00, Ortvay terem (0.81)

Kiss László, Széchenyi- és Prima Primissima-díjas csillagász

HUN-REN Csillagászati és Földtudományi Központ

Horgosról a csillagokig és tovább ‒ egy csillagász kalandozásai a nagyvilágban

Előadásomban bemutatom, hogyan válhat egy horgosi kisdiákból nemzetközileg elismert csillagász szakember, intézményvezető tudománymenedzser és egyben a média által kedvelt ismeretterjesztő tudós. Milyen impulzusok értek a falusi ég alatt, az inspiráló középiskolában és végül az egyetemen, ahol végképp eldőlt a szakmai sorsom? Mi kell ahhoz, hogy valaki helyt álljon bárhol a világban? Az életút mellett kitérek friss kutatásaimra a Naprendszerben és a más csillagok körül keringő bolygórendszerekben, földi és űrtávcsöves megfigyeléseken alapuló vizsgálataimra. Továbbá megosztom tapasztalataimat arról is, hogy a 21. században milyen módszerekkel lehet hatékonyan közvetíteni a tudományt, és hogyan kelthetjük fel az emberek, különösen a fiatalok érdeklődését a tudomány szépségei iránt.